From 46f9bf0c1856222be05805331708b1922a72f978 Mon Sep 17 00:00:00 2001
From: Jules Ivanic <jules.ivanic@gmail.com>
Date: Wed, 13 Nov 2024 18:03:35 +1100
Subject: [PATCH] Add `IdentityBoth` instance for `zio.prelude.data.Optional`

---
 .../scala/zio/prelude/AssociativeBoth.scala   | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/core/shared/src/main/scala/zio/prelude/AssociativeBoth.scala b/core/shared/src/main/scala/zio/prelude/AssociativeBoth.scala
index d4d7e46a4..6cba364cd 100644
--- a/core/shared/src/main/scala/zio/prelude/AssociativeBoth.scala
+++ b/core/shared/src/main/scala/zio/prelude/AssociativeBoth.scala
@@ -18,6 +18,7 @@ package zio.prelude
 
 import zio._
 import zio.prelude.coherent.CovariantIdentityBoth
+import zio.prelude.data.Optional
 import zio.prelude.newtypes.{AndF, Failure, OrF}
 import zio.stm.ZSTM
 import zio.stream.{ZSink, ZStream}
@@ -1191,6 +1192,24 @@ object AssociativeBoth extends AssociativeBothLowPriority {
         }
     }
 
+  /**
+   * The [[IdentityBoth]] (with [[AssociativeBoth]]) instance for [[Optional]].
+   */
+  implicit val OptionalnIdentityBoth: IdentityBoth[Optional] =
+    new IdentityBoth[Optional] {
+      val any: Optional[Any] = Optional.Present(())
+
+      def both[A, B](fa: => Optional[A], fb: => Optional[B]): Optional[(A, B)] =
+        fa match {
+          case Optional.Present(a) =>
+            fb match {
+              case Optional.Present(b) => Optional.Present((a, b))
+              case Optional.Absent     => Optional.Absent
+            }
+          case Optional.Absent     => Optional.Absent
+        }
+    }
+
   /**
    * The `AssociativeBoth` instance for And `Schedule`.
    */